The present invention is directed to the detection of foreign material. More particularly, but not exclusively, it is directed to the detection of foreign material in heterogeneous process streams such as process streams of foodstuffs. In one particular application the invention is directed to the detection of bone in a slurry of chicken meat.
During manufacturing or processing, the presence of foreign material is a persistent problem. Foreign material is sometimes accidentally introduced into a process stream, for example when small objects or contaminates fall into a process stream. Foreign material also occurs more naturally, such as when components of the raw materials are separated or otherwise processed and one type of component is inadequately removed. Examples of this latter type are prevalent in the food processing area, and include the undesirable presence of bone, pits, seeds, cores, or any other similar objects either in whole or fragmentary form in a stream of foodstuffs. Regardless of the foreign object source, it is generally desirable to detect and/or remove any foreign material to assure the quality and safety of the resulting product.
It is therefore an object of the present invention to provide a system and technique for detecting foreign material. Further, because traditionally it is more difficult to differentiate between foreign material and heterogeneous bulk material, it is a further object to provide systems and techniques that are operable to detect foreign material in an otherwise heterogeneous material. It is also an object to provide systems and techniques operable to detect foreign material in a process stream and to remove the foreign material from the process stream. It is a further object to provide systems and techniques that can reliably detect foreign material in a rapid and cost effective manner. It is a still further object to provide a novel method for the determination of other properties of a materials, such as the characterization of the degree of mixing or inhomogeneity in an inhomogenerous system. One or more of these or other objects are met by various embodiments of the present invention.
The present invention provides novel systems and techniques for detecting the presence of foreign material by detecting an off-angle ultrasound scattering response. In one embodiment, a process stream is interrogated with pulses of a focused sound field spanning a portion of the stream. The off-angle scattering response to the interrogating is then detected with a plurality of spaced receivers, with the presence of foreign material determined from the received response. In one refinement, the ultrasound receivers are focused on different sections of the insonified field and provide an indication of the relative location of detected foreign material in the process stream.
Another embodiment of the invention provides a novel technique for the detection of foreign material in a product including interrogating the product with ultrasound and determining the presence of foreign material based on the detected off-angle ultrasound scattering response. In further refined embodiments, the detected scattering response is compared to a threshold to determine the presence of foreign material. In other embodiments, the detected response from a plurality of off-angle detectors are used to determine the presence of foreign material. In still further refined embodiments, the inventive technique is used to detect foreign material in flowing inhomogeneous process slurries, and/or the technique is used to detect foreign material in foodstuffs.
There is also provided a novel system for detecting a property of a process stream. The system includes a conveyor operable to provide a process stream, an inspection device operable to measure an off-angle ultrasound scattering response of the process stream, and a processing device operable to determine a property of the material from the measured off-angle scattering response. In refined embodiments, the interrogation device is operable to transmit ultrasound to interrogate the process stream and is operable to receive an off-angle ultrasound scattering response to the interrogation with ultrasound. In further refinements, the processing device is operable to determine presence of foreign material in the process stream based on a comparison of the off-angle ultrasound scattering response to a predetermined threshold. In still further refinements, the inspection device includes a plurality of ultrasound receivers aligned non-parallel to at least one ultrasound transmitter.
Also provided is a novel method of determining a property of an inhomogeneous fluid, two phase system (solid in fluid or a fluid-fluid emulsion), and/or slurry. This novel method comprises interrogating the fluid with ultrasound, detecting an off-angle ultrasound scattering response, and determining a property of the fluid based on the off-angle ultrasound scattering response. In particular embodiments, the determined property can be, for example, one or more of the foreign material content, the degree of mixing, or the degree of inhomogeneity of the fluid. In further refined embodiments, the detected off angle scattering response scatters at an angle between about 10xc2x0 and 45xc2x0, or more preferably between 15xc2x0 and 30xc2x0 of an interrogation axis. In still further refined embodiments the method includes detecting the off-angle scattering response from a plurality of receivers spaced around an interrogation axis, the property of the fluid determined from the response from the plurality of receivers. Properties of the system determinable by this or other embodiments include the degree of mixing, degree of inhomogeneity, or consistency of a system.
Also provided is a novel system including a conduit defining a flow path with a generally rectangular cross section, one or more inspection devices operable to transmit ultrasound to interrogate a process stream in the generally rectangular portion of the flow path, a plurality of spaced receivers each operable to receive an off-angle ultrasound scattering response to interrogation with the ultrasound; and a processing device operable to determine presence of a foreign material in the process stream based on a comparison of the off-angle ultrasound scattering response to a predetermined threshold.
Also provided is a novel system comprising a conduit operable to receive a process stream, one or more inspection devices operable to interrogate a volume of material in the process stream with ultrasound, at least two receivers focused on substantially non-overlapping interrogated volumes of material each operable to receive an off-angle ultrasound scattering response to the interrogation; and a processing device operable to determine presence of a foreign material in the process stream and to provide an indication of the spatial location of the foreign material in the process stream based on a comparison of the off-angle ultrasound scattering response of each receiver to a predetermined threshold.